Digital projectors, such as digital mirror devices (DMD) and liquid crystal display (LCD) projectors, project high quality images onto a viewing surface. Both DMD and LCD projectors utilize high intensity lamps and reflectors to generate the light needed for projection. Light generated by the lamp is concentrated as a ‘fireball’ that is located at a focal point of a reflector. This light is directed into a projection assembly that produces images and utilizes the generated light to form the image. The image is then projected onto a viewing surface. Misalignment of the focal point causes degradation of the image since less light is captured, and creates ‘hot spots’ on the screen instead of a uniform brightness.
Efforts have been directed at making projectors more compact while making the image of higher and higher quality. As a result, the lamps utilized have become more compact and of higher intensity. Higher intensity lamps produce high, even extreme heat. The outer surface of the lamps can approach temperatures of 900° C. As a result, projector designs must account for the intense heat. In addition, losses due to misalignment of the fireball with respect to the reflector are amplified in systems utilizing high intensity lamps.
Some designs attempt to mitigate adverse effects of the heat by permanently placing the lamp within the reflector. A high temperature adhesive holds the lamp relative to the reflector. For example, the lamp may be secured to a lamp header with the high temperature adhesive in order to maintain the aligned relationship between the reflector and the lamp. The adhesive may be applied by hand with a brush. The adhesive thus applied may not be applied evenly throughout the gap because the adhesive resists downward flow as it sticks to the lamp and the header. As a result, the applied adhesive may be uneven and/or contain voids therein. In addition, there is limited access to the gap between the lamp and the lamp header due at least in part to the presence of the lamp. This limited access makes automation difficult. Similarly, applying adhesive with a brush is a time consuming process, which adds expense to the manufacturing process.